The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
The present invention broadly relates to well treating. More particularly the invention relates to a composition designed to cure lost circulation in general, including cementing, drilling, completion and related method for curing lost circulation in a well, such as for instance oil or gas well.
Cement in oil and gas wells is placed in the annular gap between the drilled formation and the steel casing. Its primary main function is to prevent any fluid communication between the drilled formations to provide long-term zonal isolation. Lost circulation is a common problem encountered during drilling and cementing, which accounts for significant amount of non-producing time. Many prior art's products and techniques have been developed to solve this problem. One of the most practiced techniques is to add conventional loss circulation material (LCM) to the drilling fluids, cement slurries or pills. Recently, the use of well-defined fibers has become popular due to its superior performance, and has been used successfully with drilling fluids and cement slurries. Patent applications WO2004101704, US20060157244 and patents U.S. Pat. No. 5,782,300, EP1284248 disclose such systems. Combination with other granular material was also tested (reference can be found in scientific papers from Society of Petroleum Engineers, SPE73791 and SPE54323).
Pills, fibrous materials and conventional LCM are widely used to cure lost circulation. They often are used together to improve the overall efficiency. Higher solid or fiber contents often times perform better in sealing the lost zones. However, the concentrations for these added materials must not exceed the maximum values governed by operations and equipments. For example, high concentrations of fiber will render the treatment system unpumpable and risk choking the pumps and plugging the downhole assemblies. As such, there is a need to solve this dilemma and to improve the performance of fibers and LCM without incorporating more solid materials. For this reason, it is important to develop a new technology with improved fiber performance and excellent loss circulation properties without necessarily increasing fiber concentration.